Linear-displacement sensors can be employed to determine a relative shift of two components along a substantially straight measurement path. This shift may be specified by a position or relative position (that is to say, a numerical value) of the components.
For instance, a linear-displacement sensor may be based on the eddy-current principle. DE 10 2004 033 083 A1, for instance, presents an eddy-current sensor which is arranged on an outer contour of a wheel. The measuring signal is a change in frequency of a resonant circuit as a consequence of a change in inductance by scanning of a sensor coil with an electrically conductive track. The sensor coil induces in the track an eddy current which results in a change in inductance of the sensor coil which is interconnected in the resonant circuit, the resonant frequency of which changes as a result. A robust design as regards tolerance requires, as a rule, the use of several sensor coils and several conductive tracks. A tilting and a change of the spacing of the track in relation to the sensor coil can result in inaccuracies of measurement, since the eddy-current effect exhibits a strong non-linear spacing dependence.
WO 2007/000653 A1 presents a linear-displacement sensor with coupled sensor coils which couple into an electrically conductive sliding element. Coupled sensor coils can exhibit a distinctly greater robustness in relation to changes of spacing or cases of tilting between the sliding element and the sensor coils, but may entail a higher measuring error in the case of a lateral offset of the sliding element (orthogonally to the measurement path).